Conventionally, a motion guide apparatus is known which comprises a track member having a rolling-element rolling surface formed thereon in the longitudinal direction thereof, a moving member having a load rolling-element rolling surface formed thereon so as to face the rolling-element rolling surface, the moving member being movably assembled to the track member, and a plurality of rolling elements, such as balls or cylindrical rollers, rolling between the rolling-element rolling surface and the load rolling-element rolling surface.
In the motion guide apparatus, when the moving member receives a load, the moving member is displaced relatively to the track member. In the case where a ball is used as the rolling element, when the moving member is displaced relatively to the track member, the contact point is changed, so as to change the contact angle. However, in a contact structure such as, for example, a circular arc contact structure, using a moving member and balls, the contact angle is not changed, and hence smooth rolling can be realized. On the other hand, in the case where a cylindrical roller is used, a rolling-element rolling surface and a load rolling-element rolling surface can be brought into line contact with the roller, and hence the rigidity can be improved.